Several of the injured are in critical condition, added the report from the crisis-hit country.

The new crackdown on demonstrators came as the United Nations condemned “excessive use of force” against “peaceful demonstrators” against Saleh’s rule. UN Secretary General Ban Ki-moon also expressed his deep concern about violence in Yemen.

Saleh has promised a new constitution that would shift power from the presidency to an elected parliament. Protesters say that the offer is not enough, vowing to continue to demonstrate until he resigns.

During Saturday’s crackdown, Yemeni security forces fired live bullets on anti-government protesters and killed at least 7 demonstrators, including a school boy, and injured hundreds more across the country.

Medics said that two of the protesters died of wounds on Sunday after being shot in the head by police in the southern city of Aden. Four others were in critical condition, the medics added. The casualties of the fierce crackdown are expected to rise.

Medics note that police have also used poisonous gas that paralyzes the nerve and respiratory systems and causes spasms.

Local sources have also reported that the US has provided Yemeni police with gas canisters that have been used against anti-government protesters camping out in a square in the capital city of Sana’a since February 21.

Police has reportedly used nerve gas to quell peaceful protests in Sana’a University Square. The empty canisters obtained by locals bear the “Made in U.S.A.” label.

Since the beginning of anti-Saleh demonstrations, dozens of protesters have been killed and thousands more injured in clashes with security forces or supporters of Saleh, who are armed with knives and batons.